<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0,maximum-scale=1,minimum-scale=1,user-scalable=no">
  <title>06-rem2.html</title>
  <style>
   html{
     font-size: 100px;
   }
   div{
     width: 2rem;/* 1rem等于 100px 所以2rem等于 200px */
     height: 2rem;
     font-size: .28rem;
   }
  </style>
</head>

<body>
  <div></div>
</body>

</html>